Implementation: #[feature(sync_nonpoison)], #[feature(nonpoison_mutex)]

[connortsui20]

Continuation of #134663

Tracking Issue: #134645

This PR implements a new sync/nonpoison module, as well as the nonpoison variant of the Mutex lock.

There are 2 main changes here, the first is the new nonpoison::mutex module, and the second is the mutex integration tests.

For the nonpoison::mutex module, I did my best to align it with the current state of the poison::mutex module. This means that several unstable features (mapped_lock_guards, lock_value_accessors, and mutex_data_ptr) are also in the new nonpoison::mutex module, under their respective feature gates. Everything else in that file is under the correct feature gate (#[unstable(feature = "nonpoison_mutex", issue = "134645")]).

Everything in the nonpoison::mutex file is essentially identical in spirit, as we are simply removing the error case from the original poison::mutex.

The second big change is in the integration tests. I created a macro called that allows us to duplicate tests that are "generic" over the different mutex types, in that the poison mutex is always unwrapped.

I think that there is an argument against doing this, as it can make the tests a bit harder to understand (and language server capabilities are weaker within macros), but I think the benefit of code deduplication here is worth it. Note that it is definitely possible to generalize this (with a few tweaks) to testing the other nonpoison locks when they eventually get implemented, but I'll leave that for a later discussion.

[rustbot]

r? @thomcc

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[tgross35]

r? tgross35

[tgross35]

Looks pretty good to me, most comments here are related to docs. This will need some history cleanup, there isn't any need to preserve the current state of #134663 in history (I assume this was just done for now to show what changed since then)

[bors]

📌 Commit d073d29 has been approved by tgross35

It is now in the queue for this repository.

[bors]

⌛ Testing commit d073d29 with merge 7278554...

[tgross35]

@bors r-

^ For whatever that is, it's already tested and merged